(a) Field of the Invention
The present invention relates to a compactly arranged zoom lens system with a range of field angle from 24.degree. to 62.degree. including the field angle of standard lens systems, i.e., about 47.degree., of which the overall length is short, outer diameter is small, and aperture ratio is F/4.
(b) Description of the Prior Art
In recent years, there is a great demand for zoom lens systems in the field of photographic lens systems and the like because they ensure high mobility and convenience at the time of use. Especially, zoom lens systems with ranges of field angles including the field angle about 47.degree., which is the field angle of standard lens systems, are in increasing demand. For this kind of zoom lens systems, there is such tendency that a zoom lens system with a large zoom ratio will be required in near future. When, however, the zoom ratio is made large, the zoom lens system as a whole tends to become large in size, and this is not desirable. In other words, it is required to provide a zoom lens system having a large zoom ratio and, at the same time, arranged compactly. As a known zoom lens system designed for the purpose of fulfilling the above-mentioned requirements, there is a zoom lens system disclosed for example in Japanese published unexamined patent application No. 156912/80. However, the above-mentioned zoom lens system is not satisfactorily compact because the front lens thereof has a large diameter and it is necessary to use a filter of 72 mm in diameter.